[packagekit] Slight interface change ::Transaction()

[Richard Hughes]

I've found an difference in the API docs and what the daemon actually
does:

Transaction is the signal sent when we do GetOldTransactions for the log
viewer. In the API docs it says that we send the duration as seconds.

In the database we store this as ms, and also emit this as ms in
the ::Finished() signal. We've also been emitting this as ms since
version 0.1.something.

So, I'm just going to change the API description from:

"The duration of the transaction in seconds."

to

"The duration of the transaction in milliseconds."

I don't really consider this an API break, as it doesn't change what the
daemon sends, it just fixes up the documentation. This won't also alter
the client tools, as they've been accepting values in milliseconds for a
while now.

Just a heads up.

Richard.